<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
        * {
            padding: 0;
            margin: 0;
            text-align: center;
        }

        .wrap {
            width: 500px;
            margin: 100px auto 0;
        }

        table {
            border-collapse: collapse;
            border-spacing: 0;
            border: 1px solid #c0c0c0;
            width: 500px;
        }

        th,
        td {
            border: 1px solid #d0d0d0;
            color: #404060;
            padding: 10px;
        }

        th {
            background-color: #09c;
            font: bold 16px "微软雅黑";
            color: #fff;
        }

        td {
            font: 14px "微软雅黑";
        }

        tbody tr {
            background-color: #f0f0f0;
            cursor: pointer;
        }
        
        .current {
            background-color: red!important;
        }
    </style>
	</head>
	<body>
		<div class="wrap">
        <table>
            <thead>
                <tr>
                    <th>序号</th>
                    <th>姓名</th>
                    <th>课程</th>
                    <th>成绩</th>
                </tr>
            </thead>
            <tbody id="target">
                <tr>
                    <td>
                        1
                    </td>
                    <td>吕不韦</td>
                    <td>语文</td>
                    <td>100</td>

                </tr>
                <tr>
                    <td>
                        2
                    </td>
                    <td>吕布</td>
                    <td>日语</td>
                    <td>100</td>
                </tr>
                <tr>
                    <td>
                        3
                    </td>
                    <td>吕蒙</td>
                    <td>营销学</td>
                    <td>100</td>
                </tr>
                <tr>
                    <td>
                        4
                    </td>
                    <td>吕尚</td>
                    <td>数学</td>
                    <td>100</td>
                </tr>
                <tr>
                    <td>
                        5
                    </td>
                    <td>吕雉</td>
                    <td>英语</td>
                    <td>100</td>
                </tr>
                <tr>
                    <td>
                        6
                    </td>
                    <td>吕超</td>
                    <td>体育</td>
                    <td>100</td>
                </tr>
            </tbody>
        </table>
    </div>
	<script type="text/javascript">
		//需求: 让tr各行变色,鼠标放入tr中,高亮显示.
		
		//1.隔行变色
		var tbody = document.getElementById("target");
		var trArr = tbody.children;
		
		//循环判断并各行赋值属性(背景色)
		for(var i = 0;i<trArr.length;i++){
			if(i%2!==0){
				trArr[i].style.backgroundColor = "#a3a3a3";
			}else{
				trArr[i].style.backgroundColor = "#ccc";
			}
			//鼠标进入高亮显示
			//难点:鼠标移开的时候要恢复原始颜色.
			//计数器(进入tr之后，立刻记录颜色，然后移开的时候使用记录好的颜色)
			var color = "";
			trArr[i].onmouseover = function () {
				//赋值颜色之前,先记录颜色
				color = this.style.backgroundColor;
				this.style.backgroundColor = "#fff";
			}
			trArr[i].onmouseout = function (){
				this.style.backgroundColor = color;
			}
		}
		
		
	</script>
	</body>
</html>
